By: Daniel Overbey AIA, NCARB, LEED AP BD+C The term indoor environmental quality (IEQ) is very broad in scope. The design and construction profession commonly lumps four key topics under this umbrella terms:
- Indoor air quality: To ensure that occupiable indoor air volumes are relatively free of contaminants and do not threaten human health or building damage functions.
- Thermal comfort: To ensure that indoor environments can be properly managed to achieve and maintain rates of ambient air temperature, air changes, air velocities, relative humidity, and mean radiant temperature that are conducive to human thermal comfort (with consideration of expected activity and clothing levels).
- Visual comfort: To ensure that indoor spaces offer adequate access to quality views as well as daylight that achieves useful illumination levels with relatively even light distribution within occupants’ field of vision.
Increasingly, however, design professionals – and the green building industry in particular – are beginning to recognize the virtues of a fourth topic – acoustical comfort – and for good reason. Have you ever struggled to hear a presentation due to echo or lack of sound carrying across a venue? Have you ever been disturbed by noise transmitting from a nearby space (I’m thinking of kids running up and down the hall outside of my hotel room at 4:30 AM)? Have you ever felt like a space was too quiet to provide conversational privacy? If so, then you have been confronted with an acoustical comfort issue. Specific interest in acoustical comfort by the green building industry is not new. LEED for Schools and LEED for Healthcare have long exhibited an acoustic performance credit. Obviously, a classroom’s appropriately controlled acoustics carry significant consequences in terms of a student’s ability to listen to their teachers. For healthcare facilities, acoustical comfort is critical for establishing an indoor healing environment free of intrusive or disruptive levels of sound. Yet in LEED v4 the Acoustic Performance credit (EQc9) is being expanded into several additional versions of the rating system – such as New Construction, Commercial Interiors, Hospitality, and Healthcare. This underscores the green building industry’s increasing understanding that our sense of hearing is a significant factor regarding comfort, wellness, and ability to perform. There are a number of ways in which acoustical comfort can be addressed in terms of architectural and interior design. See the case study below for an example of a multifaceted approach to robust acoustical control for the faculty studios at the IU Jacobs School of Music East Studio Building. Case Study: Faculty Studios at the IU Jacobs School of Music East Studio Building The Jacobs School of Music East Studio Building at Indiana University consists over 80 Faculty Studios, all of which are acoustically isolated from one another. Below is a description of how Browning Day Mullins Dierdorf Architects responded to the Faculty Studios’ stringent acoustical performance requirements:
- The floor structure consists of pre-finished hardwood maple over two layers of plywood placed on resilient pads that keep it isolated from the concrete floor slab below.
- The walls are designed as a room within a room. The inner wall is metal stud construction with two layers of 5/8″ gypsum board on the interior face and batt insulation in the cavity. The inner wall is held away from a CMU demising wall that separates it from the neighboring Faculty Studio.
- Two walls within each Faculty Studio are canted vertically to reflect sound towards the ceiling.
- The ceiling visually appears to be a standard 2′ x 2′ acoustical tile ceiling system, but each tile is backed with a 1/2″ piece of gypsum board and covered with batt insulation to reduce the transmission of sound to the Faculty Studios above.
- A series of wood rails have been added to two walls in each studio. These rails allow the user to hang speakers, LCD monitors, adjustable acoustical panels, artwork, and other items without making any penetrations into the acoustical wall construction.
- Each room features two large format acoustical wall panels that can be arranged to absorb sound as required for the users preference.
- The 2 1/4″ thick doors feature a bottom gasket and the door frames feature a perimeter gasket that acoustically isolate the sound in the room from the sound in the corridor.
(Full disclosure: I served as the LEED consultant on this project – which is expected to achieve LEED Gold certification.) In aggregate, these design decision adequately isolate sound (conversational and instrumental) within each Faculty Studio. Criteria for sound transmission between spaces, reverberation time within each space, and the overall specified Noise Reduction Coefficient criteria were all achieved through this multifaceted design solution. Photos: The recently completed Jacobs School of Music East Studio Building at Indiana University. Photo courtesy of Browning Day Mullins Dierdorf Architects Interior rendering of the Faculty Studio. Image courtesy of Browning Day Mullins Dierdorf Architects